American Heiress: The Wild Saga of the Kidnapping, Crimes and Trial of Patty Hearst by Jeffrey Toobin:
The comrades took to the task with enthusiasm. In particular, the female comrades made a special effort to show that they could contribute as much to the action as the men. Wendy Yoshimura, who had learned to make bombs with her former flame Willie Brandt, took the role of lead designer. She envisioned simple pipe bombs, which would consist of gunpowder stuffed inside two-inch pipes, attached by wires to a battery for a spark and an alarm clock as a timing device. Kilgore and Kathy Soliah spent a day driving around Marin County buying the components.
True to form, Bill Harris had a different approach. Based on his study of the cookbook, he decided he could improve on Yoshimura’s design. Bill and Emily worked on his idea at Geneva Avenue—which paralyzed Patricia with fear of an accident—and then experimented with detonation devices on some old mattresses in the tiny backyard. Bill’s test resulted in a small, smoldering fire and a summons to the fire department. According to Patricia, Emily told the firefighters that local kids smoking cigarettes had started the little blaze.